The invention relates to a magnetic trigger which has at least a yoke having an armature opening, an armature disposed inside yoke, wherein the armature is coaxially surrounded by at least one section of the coil body having at least one excitation coil and is biased by the force of a preloaded spring element, wherein when current is not flowing through the excitation coil, the armature remains in a first end position due to the magnetic holding force of a permanent magnet, wherein the permanent magnet together with a socket extending between the armature and the permanent magnet are arranged in the area of the first end of the armature, and the second end position of the armature is attained by briefly flowing a current through the excitation coil together accompanied by a reduction of the magnetic holding force and the simultaneously effective spring force.
Many variants of bistable magnetic triggers or trigger magnets constructed in this manner are employed in high-power switches and other devices.
Solutions have been disclosed in the prior art, for example in U.S. Pat. No. 3,922,957. CA 0227 1327, U.S. Pat. No. 3,893,052, U.S. Pat. No. 3,792,390, JP 2006 051 055, U.S. Pat. No. 6,646,529, U.S. Pat. No. 5,387,892, JP 2005 166 429. JP 2005 268 031 or JP 2005 340 703.
Important requirements for trigger magnets are hereby a short trigger time, low energy consumption for triggering as well as a large ratio between the released mechanical energy and the electrical trigger energy or energy yield.
Short trigger times can be achieved, for example, with a low armature mass, as taught in JP 2005 268 031 or CA 0227 1327 which use a drilled-out armature.
The object of switching with only a low trigger energy can be achieved with a bypass in the magnetic circuit, as disclosed in U.S. Pat. No. 3,922,957 or U.S. Pat. No. 3,792,390.
A large amount of mechanical energy is released with a predetermined spring force, when the spring constant is small and the stroke is large. This is achieved, in particular, with externally arranged springs, as disclosed for example in JP 2005 166 429.
The solutions disclosed in the state-of-the-art are frequently strongly optimized only with respect to a single parameter, for example installation space, force or trigger time. The trigger parameters then scatter over a wide range. A significant underlying reason is the play in the armature guidance resulting from the structure. Due to the tolerances in the housing and in the alignment of the parts during assembly, the armature is slightly tilted with respect to the socket. Transverse forces between the armature and the housing additionally tilt the armature. Conventional structure are unable to compensate for this tilt. Tighter guides would also cause jamming.
The spring is guided directly on the armature, unless the spring is located outside the magnetic circuit or inside the armature. The spring constant then remains relatively high and the energy yield is relatively small. However, the solutions advantageous for the spring constant make it difficult to guide the armature and/or orient the armature on the socket. However, large metallic friction is observed when the spring is guided in the armature. The spring then tends to buckle. Both effects are undesirable.